Bauhaus-Universität Weimar

INFLUENCE OF THE EPIGLOTTIS IN DEGLUTITION. 351 
voluntarily or by the contact of a stimulus, the action of the whole 
group of muscles belonging to deglutition, with the constrictors of 
the pharynx also, ensues, and any portion of food, drink, or saliva, 
wrhich has passed beyond a certain limit in the mouth, is swallowed 
without our being able to prevent it. 
It appears certain that both the second and the third acts of deglu¬ 
tition are, as Dr. Marshall Hall (Mem. on the Nervous System, p. 
83,) pointed out, always excited or reflex movements, and that when 
they seem to be performed voluntarily, although there is no food to 
swallow, saliva constitutes the necessary stimulus. According to 
this view, it is easy to understand why, if there is no food in the 
mouth, the fauces must be moist, and also why the movement cannot 
under these circumstances be repeated many times in succession. 
The nerves which convey to the medulla oblongata the impression 
which excites the movements of deglutition, are, according to Dr. 
Reid, (jEd. Med. <§• Surg. Journ. vol. li. p. 273,) the glosso-pharyn- 
geal, those branches of the fifth which are distributed to the fauces, 
and probably those branches of the superior laryngeal nerve which 
reach the pharynx; while the motor influence transmitted from the 
medulla is conveyed by the pharyngeal branches of the vagus; by 
the branches of the hypo-glossal nerve, distributed to the tongue, 
thyro-hyoid, sterno-hyoid, and sterno-thyroid muscles; by the motor 
filaments of the recurrents ramifying in the muscles of the larynx; 
by some branches of the fifth supplying the elevator muscles of the 
lower jaw; by the branches of the portio dura which ramify in the 
digastric and stylohyoid muscles and muscles of the lower part of 
the face; and probably by some branches of the cervical plexus 
which unite with the descendens noni; all the muscles supplied by 
the nerves here enumerated being engaged in the function of deglu¬ 
tition. Dr. Reid’s experiments [Ibid. vol. xlix. p. 150; vol. li. p. 274 
and 329,) lead him to believe that both the incident and reflex motor 
nervous action are in the oesophagus conveyed by filaments of the 
vagus nerve, at least in the rabbit.* 
In the true serpents, in which the superior maxillary bones can 
be in some measure separated from each other like the two halves 
of the inferior maxilla, and in which, by means of the long ossa 
quadrata extending from the movable temporal bones to the lower 
jaw, the throat is capable of great dilatation, the act of swallowing 
consists, as Rudolphi aptly remarked, in the organs of deglutition 
being drawn over the bulky prey. 
Influence of the epiglottis in deglutition.—M. Magendie* has 
confirmed the observation made originally by Galen that the rima 
glottidis itself is closed during deglutition. But he has gone too fair 
in admitting that removal of the epiglottis does not prevent degluti¬ 
tion being performed. Even allowing this conclusion, which M. 
Magendie has deduced from experiments on animals, to be correct, 
it is equally certain, as the numerous records of cases in which the 
* For further information respecting the functions of the vagus nerves, see the 
Fourth Book, 2d Section, Chap. II. 
* Mémoires sur l’usage de l’Epiglotte dans la Déglutition. Paris, 1813.
        

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